Reciprocating saws are well known in the art. The straight back and forth, or reciprocal, action of its blade, characterizes a reciprocating saw. Some reciprocating saw also have the ability to assume an orbital blade motion, characterized by a slightly circular motion as the blade moves back and forth. Reciprocating saws include a blade clamp suitable for securing the blade to the saw, and a brace, commonly referred to as a shoe, used to brace the reciprocating saw against a work piece during a cut. The shoe is generally located some adjustable distance from the blade clamp. The adjustable nature of the shoe serves two purposes: it allows a user to control the depth of a cut, and it makes it possible to evenly distribute wear on the blade. FIG. 1 illustrates a typical reciprocating saw 50, including a saw blade 54 and a shoe 56 connected to a saw 52.
While using the reciprocating saw, it is frequently desirable to adjust the distance of the shoe from the blade clamp. For instance, a user might switch from making a cut in a hard to reach place, requiring a longer length of blade, to making a plunge cut into a material at a shallow depth, requiring a much shorter blade length. In addition, frequently adjusting the distance of the shoe from the blade clamp has the benefit of shifting the range of contact of the teeth as the blade reciprocates; thereby lengthening the life of a typical reciprocating saw blade.
Adjustment of the distance from the shoe to the blade clamp may be accomplished through the positional adjustment of a shoe bracket, to which the shoe is attached, and which is capable of movement parallel to the blade of the saw. In many typical applications, a hand tool such as a wrench, screwdriver, or other suitable device may be used to alternately tighten and loosen a fastener securing the shoe bracket, allowing adjustment of its position, and consequently the position of the shoe. However, the conventional use of a wrench, screwdriver, or some other hand tool to adjust the position of the shoe bracket may not be desirable. In addition to the added time expended in locating the hand tool, if the adjustment must be made at a remote location, the absence of such a tool may effectively prevent adjustment of the shoe bracket. While it is possible to add an integrated wrench assembly to a reciprocating saw for tightening and loosening the fastener securing the shoe bracket, the wrenching action required does not correspond to the normal gripping action of a typical user.
In the prior art, this limitation has typically been overcome by providing a keyless shoe lock, consisting essentially of a shoe bracket including a plurality of notches or grooves, and a pin suitable for engaging the shoe bracket when seated in a notch or groove. The pin is generally attached to a lever, the action of which corresponds with the normal gripping action of a typical user. But this method also presents limitations. First of all, the pin must be of a certain diameter to meet the necessary strength requirements for a tool that vibrates as rapidly and as strongly as a reciprocating saw does—especially when cutting through particularly unwieldy material. Second, the notches or grooves in the shoe bracket must be a certain minimum distance apart to provide enough material contact with the pin to ensure the shoe bracket does not slip during operation.
Thus, the combination of two factors, namely the diameter of the pin and the spacing of the notches or grooves in the shoe bracket, severely limits the number of discrete positions the shoe bracket and shoe are capable of assuming. As previously noted, one of the reasons that it is desirable to adjust the shoe bracket and shoe is that shifting the range of contact of the blade lengthens the life of a saw blade. As the teeth may be much smaller than the distance between discrete positions attainable by the shoe as taught by the prior art, the use of a pin and a shoe bracket including notches or grooves may have served only to shift the range of contact between sets of teeth on the reciprocating saw blade.
Consequently, it would be desirable to provide a keyless shoe lock for a reciprocating saw, enabling the positional adjustment of a shoe in small increments.